4.15. Platform-specific Flags

Some flags only make sense for particular target
platforms.

-msse2:

(x86 only, added in GHC 7.0.1) Use the SSE2 registers and
instruction set to implement floating point operations
when using the native code generator. This gives a
substantial performance improvement for floating point,
but the resulting compiled code will only run on
processors that support SSE2 (Intel Pentium 4 and later,
or AMD Athlon 64 and later).